1. Field of Invention
The invention relates to a positioning device for minimally invasive surgery and, more particularly, to a three-dimensional positioning device for minimally invasive neurosurgery.
2. Description of Related Art
In recent years, a medical operation method has developed toward minimally invasive surgery. Minimally invasive surgery is characterized in a small incision, such as skull tumor electro-burning surgery, nail spine implant surgery, or artificial dental implant surgery. It has several advantages such as a small incision, short healing time, low probability to infect and less blood loss. The smaller incision is difficult to invade and is difficult to mount an instrument or implant. Thus, it is necessary to have a better and precise positioning device to increase the surgery success rate.
Take the skull tumor electro-burning surgery for an example. Common brain diseases are inclusive of brain tumors, Parkinson's disease, epilepsy, etc. These diseases may cause patients to have several symptoms such as trembling, headache, vomiting, dysopia or unconsciousness. These symptoms can result in lowering the quality of life by a wide margin. Seriously, these diseases may endanger the life of the patient. Furthermore, if conservative therapy can't improve the health of the patient, it is necessary to utilize invasive surgery to treat these diseases.
Conventionally, the surgeon has to diagnose the position of the nidus by computerized tomography (CT scan) and clinical experience. Then, the surgeon utilizes a cauterizing needle and a frame to mount on the skull of the patient for reaching the position of the nidus and to get rid of the nidus.
Recently, computer technology has developed and advanced well. A three-dimensional image and auxiliary positioning system has developed to assist the operation of the invasive surgery. Conventional procedures of computer-assisted skull surgery are described as follows. The patient has to be mounted on a rectangular frame to execute a brain CT scan before surgery. After image processing in the computer, the three-dimensional relative position among the rectangular frame, the skull and the nidus is obtained. Surgeons have to plan the invasive path and depth of the cauterizing needle by utilizing the computer to calculate the rotation angle or displacement of each movable element in the mechanism when the rectangular frame mounts on the patient. Until in the surgery, surgeons utilize the rectangular frame, an optical ball device and a camera to take a picture. Surgeons also can utilize LEDs to emit signals and to co-operate with a receiver to obtain the position of the rectangular frame. At the same time, the position of the skull 110 and the position of the nidus can also be obtained. Then, a positioning device is moved onto the rectangular frame mounted on the patient. Finally, as shown in FIG. 12, the cauterizing needle is mounted, and the cauterizing needle is utilized to invade to the nidus for treating.
Besides, another conventional three-dimensional positioning device utilizes a rectangular frame and a semicircular frame to position. Such conventional three-dimensional positioning device in use has to cover the whole skull. It reduces the operating space for the surgeons. Furthermore, it is without the design of the cauterizing needle adjustment mechanism. It results in surgeons having to operate the cauterizing needle manually. Therefore, the invasive depth and invasive speed can't be accurately controlled.
In addition, another conventional three-dimensional positioning device utilizes a link mechanism to make the cauterizing needle be movable or fixed. Such three-dimensional positioning device can provide a wider movable range for the cauterizing needle. However, it also leads to a problem of cumbersome volume. It reduces the operating space for the surgeons. It also leads to a poor rigidity due to the link mechanism.
Besides, another conventional three-dimensional positioning device utilizes an upper member and a lower member to rotate. The upper member is semicircular. The upper member can provide a curve movement. Such conventional three-dimensional positioning device is small and can be directly mounted on the incision of the skull. It utilizes a rotatable knob to adjust the cauterizing needle into the nidus with a small extent. However, due to the small volume, it leads to a smaller scale. Smaller scale may lead to difficult adjustment in practical operation. At the same time, such conventional three-dimensional positioning device has many parts. It is time-consuming to assemble the conventional three-dimensional positioning device.
To summarize, conventional three-dimensional positioning devices have many problems such as low precision, poor rigidity, and so on. Furthermore, as shown in FIG. 12, the conventional three-dimensional positioning device 100 has many directions D to adjust. It results in many problems such as a complex structure, difficult operation procedures and low precision. Due to the complex structure, difficult operation procedures and low precision, it may result in a longer operation time to decrease the surgery success rate. Seriously, it may endanger the patient's life. Thus, the need for improvement still exists.